Rezko's case has gained national prominence because of his close ties with Sen. Barack Obama and his role in helping to raise campaign money for the candidate. Obama is not considered a subject of the FBI investigation.

Rezko was arrested Monday after FBI agents learned Rezko had secretly received more than $3.5 million in a wire transfer from Beirut, Lebanon, a violation of his bail terms, according to prosecutors who said Rezko may have been preparing to flee the country prior to the trial.

The money to Rezko came from an Iraqi businessman, Nadhmi Auchi, who was convicted on French fraud charges and investigated in the oil-for-food scandal, though no charges were ever brought against him and he has denied wrongdoing.

According to an FBI affidavit filed in the case, Rezko sought to get a visa for Auchi to visit the United States by contacting "certain Illinois government officials."

A spokesman for Sen. Obama, Bill Burton, told ABCNews.com that Obama had not taken any action on behalf of Auchi.

A Middle East Web site shows a photograph of what it described as Auchi visiting Illinois government officials in April 2004, with a man who resembles Rezko on the right of the photo. Some of our readers have said that man is not Rezko.

The Web site says Auchi met with Illinois Gov. Rod Blagojevich, another politician close to Rezko, along with "businessmen and Congressmen also present in the dinner held in his honor."

There is no mention of Obama being present at the dinner.

Rezko, who has pleaded not guilty to the corruption charges he faces, appeared in an orange jumpsuit in the Chicago courtroom.

His lawyer, Joe Duffy, pleaded with U.S. District Judge Amy J. St. Eve to allow Rezko to remain free prior to the trial so he can help prepare his defense.

"I cannot give him his constitutional defense," Duffy told the judge.

Prosector Assistant U.S. Attorney Reid J. Schar said "Rezko can't be trusted," and the judge ordered him returned to the federal Metropolitan Correction Center in Chicago where he will remain until his trial.